class Phone:

    def __init__(self, __is_5g_enable=None):
        self.__is_5g_enable = __is_5g_enable

    def __check_5g(self):
        if self.__is_5g_enable:
            print("5g开启")
        else:
            print("5g关闭，使用4g网络")

    def call_by_5g(self):
        self.__check_5g()
        print("正在通话中")
